Class: FileCache

Inherits:
Object
  • Object
show all
Defined in:
lib/FileCache.rb

Overview

creates and manages a local cache of files, so an URL can be requested, if it is in the cache, the local copy is used, otherwise the file is downloaded to the local cache

Constant Summary collapse

@@file_system_image_urls = 
nil

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(url_cache_dir, native_file_cache_dir) ⇒ FileCache

Returns a new instance of FileCache.



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# File 'lib/FileCache.rb', line 44

def initialize(url_cache_dir,native_file_cache_dir)
  @url_cache_dir=url_cache_dir
  @native_file_cache_dir=native_file_cache_dir
  @url_cache_list="#{url_cache_dir}/cache.urls"
  Dir.mkdir(url_cache_dir) unless File.exists?(url_cache_dir)
  raise "cache directory #{url_cache_dir} invalid" unless File.directory?(url_cache_dir)
  Dir.mkdir(native_file_cache_dir) unless File.exists?(native_file_cache_dir)
  raise "cache directory #{native_file_cache_dir} invalid" unless File.directory?(native_file_cache_dir)
end

Instance Attribute Details

#native_file_cache_dir ⇒ Object

Returns the value of attribute native_file_cache_dir.



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# File 'lib/FileCache.rb', line 19

def native_file_cache_dir
  @native_file_cache_dir
end

#url_cache_dir ⇒ Object

Returns the value of attribute url_cache_dir.



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# File 'lib/FileCache.rb', line 19

def url_cache_dir
  @url_cache_dir
end

#url_cache_list ⇒ Object

Returns the value of attribute url_cache_list.



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# File 'lib/FileCache.rb', line 19

def url_cache_list
  @url_cache_list
end

Instance Method Details

#cache_name_for_icon(native_file) ⇒ Object 



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# File 'lib/FileCache.rb', line 40

def cache_name_for_icon(native_file)
  "#{native_file_cache_dir}/#{native_file.icon_tag}.icon.#{native_file.icon_format.to_s}"
end

#cache_name_for_native_file(native_file, extension) ⇒ Object 



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# File 'lib/FileCache.rb', line 34

def cache_name_for_native_file(native_file,extension)
  image=native_file.file_system_image
  index=image.files.index(native_file)
  "#{native_file_cache_dir}/#{Digest::MD5.hexdigest(image.filename)}-#{index}.#{extension}"
end

#cache_name_for_url(url) ⇒ Object 



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# File 'lib/FileCache.rb', line 22

def cache_name_for_url(url)
  if ( url=~/^file:/) then
    local_name=CGI.unescape(url.sub(/file:\/+/,""))
    local_name="#{File::Separator}#{local_name}" unless ((local_name[1].chr==':') || (local_name[0].chr==File::Separator))
#    puts "#{url}->#{local_name}"
    local_name
    
  else
    "#{url_cache_dir}/#{Digest::MD5.hexdigest(url)}.cached"
  end
end

#file_system_image_urls_in_cache ⇒ Object 



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# File 'lib/FileCache.rb', line 88

def file_system_image_urls_in_cache
  if @@file_system_image_urls.nil? then
    make_file_system_image_list unless File.exists?(@url_cache_list)
    @@file_system_image_urls=File.open(@url_cache_list,"r").readlines.collect{|url| url.chomp}
  end
  @@file_system_image_urls
end

#force_icon_to_cache(native_file) ⇒ Object 



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# File 'lib/FileCache.rb', line 129

def force_icon_to_cache(native_file)
  cache_filename=cache_name_for_icon(native_file)
  if ! File.exists?(cache_filename) then    
      local_file=File.open(cache_filename,"wb")      
      local_file<<native_file.to_icon
      local_file.close        
    end
    return cache_filename
end

#force_native_file_to_cache(native_file, method_to_cache_on_native_file, extension) ⇒ Object 



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# File 'lib/FileCache.rb', line 119

def force_native_file_to_cache(native_file,method_to_cache_on_native_file,extension)
  cache_filename=cache_name_for_native_file(native_file,extension)
  if ! File.exists?(cache_filename) then    
      local_file=File.open(cache_filename,"wb")      
      local_file<<native_file.send(method_to_cache_on_native_file)
      local_file.close        
    end
    return cache_filename
end

#get_file_system_image(url) ⇒ Object 



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# File 'lib/FileCache.rb', line 80

def get_file_system_image(url)
  file=get_url(url)    
  image=RipXplore.best_fit_from_file(file)
  @@file_system_image_urls<<url if (!@@file_system_image_urls.nil? && !@@file_system_image_urls.include?(url))    
  return image
end

#get_url(url) ⇒ Object 



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# File 'lib/FileCache.rb', line 62

def get_url(url)
  local_file_name=cache_name_for_url(url)
  if !File.exists?(local_file_name) then
    RipXploreLog.log "downloading #{url}"
    remote_file=open(url,"rb")
    local_file=File.open(local_file_name,"wb")      
    local_file<<remote_file.read
    local_file.close
    local_file_info_filename="#{local_file_name}.info"
    local_file_info_file=File.open(local_file_info_filename,"w")
    local_file_info_file<<url
    local_file_info_file.close
  end
  file=FileCacheItem.open(local_file_name,"rb")
  file.set_path(url)
  file
end

#make_file_system_image_list ⇒ Object 



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# File 'lib/FileCache.rb', line 96

def make_file_system_image_list
  urls=[]
  Dir.glob("#{url_cache_dir}/*.cached.info").each do |info_file|
    url=File.open(info_file,"r").read.chomp
    urls<<url if (FileSystemImage.is_file_system_image_filename?(url))
  end
  File.open(@url_cache_list,"w") {|f| f<< urls.join("\n")}
end

#purge_icon_from_cache(native_file) ⇒ Object 



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# File 'lib/FileCache.rb', line 146

def purge_icon_from_cache(native_file)
	filename=cache_name_for_icon(native_file)
	File.delete(filename) if File.exists?(filename)
	
end

#purge_native_file_from_cache(native_file) ⇒ Object 



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# File 'lib/FileCache.rb', line 139

def purge_native_file_from_cache(native_file)
  Dir.glob(cache_name_for_native_file(native_file,'*')).each do |filename|
    RipXploreLog.log "purging local #{filename}"
    File.delete(filename)  
  end
end

#purge_url(url) ⇒ Object 



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# File 'lib/FileCache.rb', line 54

def purge_url(url)
  local_file_name=cache_name_for_url(url)
  if File.exists?(local_file_name) then
    RipXploreLog.log "purging local copy of #{url}"
    File.delete(local_file_name)
  end
end

#random_file_system_image(collection_type = nil) ⇒ Object 



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# File 'lib/FileCache.rb', line 106

def random_file_system_image(collection_type=nil)
  all_image_urls=file_system_image_urls_in_cache    
  all_image_urls.length.times do
    begin
      index=rand(all_image_urls.length)
      image=get_file_system_image(all_image_urls[index%all_image_urls.length])
      return image if ((collection_type==nil) || (image.send(collection_type).length>0))
    rescue #silently swallow any exception
    end    
  end
  raise 'no suitable image found in cache'
end